De Zeeuw et al. U.S. Pat. No. 6,301,952, issued on Oct. 16, 2001, for a Gas Chromatographic Device, disclosed that prior to their invention, chromatography columns in GC/MS systems were often very long to provide the necessary pressure drop between the inlet, where the inlet pressure of the chromatography column was above atmospheric, to the outlet of the chromatography column, where the outlet pressure of the chromatography column was essentially vacuum because the chromatography column ended in the ionization chamber of the mass spectrometer, thereby resulting in long periods of time needed to perform the sample analyses. De Zeeuw et al. U.S. Pat. No. 6,301,952, in its background section, indicated that although smaller bore columns having a reduced length could be used to provide the pressure drop, such columns had disadvantages of a limited sample capacity, installation and operation problems, and a problem regarding eluted peaks being too fast to record using mass spectrometry systems.
De Zeeuw et al. U.S. Pat. No. 6,301,952, which is incorporated herein by reference, discloses a gas chromatographic device comprising an inlet system, a chromatography column, and a pressure reducing means disposed therebetween for reducing pressure between an inlet of the pressure reducing means and the outlet of the chromatography column. In an alternative embodiment disclosed in the De Zeeuw et al. U.S. Pat. No. 6,301,952, a gas chromatographic device comprises an inlet, a wide-bore column having an inlet and an outlet, and a pressure reducing means being coupled to the outlet of the column for providing a vacuum condition at the outlet of such pressure reducing means. The pressure reducing means disclosed in the De Zeeuw et al. U.S. Pat. No. 6,301,952 is a coiled tubular shaped restrictor column which is integrally attached with connectors (either permanently or using ferrules or press-fit connectors) to the chromatography column. The restrictor column is susceptible to contamination at its inlet, thereby requiring repeated clipping off of a short length of the restrictor column at its inlet to clear the sample path. In the event that the restrictor column becomes too short due to repeated clipping, the restrictor column must be replaced requiring mechanically removing the connector (e.g., a ferrule-based connector) or clipping off the permanent connector or press-fit connector in order to connect a new restrictor column to the chromatography column using either a new permanent connection or a new ferrule-based connection or new press-fit connection. With each restriction column trimming, the flow path is shortened, resulting in potential run-to-run variance. With the ferrule-based connectors, the replacement process is labor intensive and requires prolonged opening of the GC oven. Further, since the restrictor column resides in the GC oven, it is therefore subject to the same temperature ramp of the analysis. Accordingly, this results in a complex gas flow profile that may be difficult to reproduce over repeated runs where the length of the restrictor column changes each time it is clipped by the above-mentioned trimming process.